JP2000000860A - Screw injection device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To plasticize the measured resin uniformly by closing a gap formed between a screw and an inner wall for accumulating a resin material in a cylindrical part through which the resin material passes, with the help of a spring force and opening the gap by a resin pressure resisting the spring force at the time of measurement. SOLUTION: A resin material to be supplied into a barrel 11 from a material supply aperture 15 is heated by a heating device, and at the same time, is melted by a shearing heat generated by a screw 16 to be rotated through the splines 19 of a plunger 17. Further, the molten resin is moved forward to push open a check block 21 which closes a resin passage 20 by the pressing force of a spring 22, and is accumulated in a cylindrical part 24 through the resin passage 20 while moving the plunger 17 backward. During this period, the screw 16 rotates without moving in the axial direction and the measured resin is not plasticized ununiformly. In addition, the resin passage 20 which is opened in the measuring step is closed by the pressing force of the spring 22 as no supply of the resin under high pressure from the screw 16 side so that no back flow of the resin from the resin passage 20 side to the screw 16 side occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a screw type injection device for injecting a resin material of an injection molding machine.

[0002]

2. Description of the Related Art A conventional screw-type injection device of this type will be described with reference to FIGS. 5 and 6. Reference numeral 1 denotes an injection device.
The screw 5 is rotatable on the inner diameter surface,
Further, it is fitted so as to be movable by a distance S in the axial direction. A hopper 7 for supplying a resin material 6 is provided at the other end of the heating barrel 2. The resin material 6 introduced into the heating barrel 2 is heated by a heating device (not shown) provided in the heating barrel 2. While being melted by shear heat insulation by the rotation of the screw 5 and transferred forward (to the left in the figure).
As shown in FIG. 5, the screw 5 is accumulated in front of the screw 5 as the molten resin 6a, and the screw 5 is retracted rightward in the drawing by the resin pressure of the molten resin 6a accumulated in the front.

When the screw 5 is retracted by a predetermined distance S, the rotation of the screw 5 stops (completion of the measuring step), and then the screw 5 moves forward to inject the molten resin 6a accumulated in front of the screw 5, and FIG. From the state of FIG. 5 to the state of FIG.
The molten resin 6a is injected through the nozzle 3 into a mold cavity (not shown).

[0004]

However, the molten resin 6a accumulated in front of the screw 5 is not plasticized uniformly on the front side (nozzle side) and the rear side (screw side).
The molded product has poor strength and the like. That is, the effective length of the screw was L at the beginning of the measuring step, but the effective length of the screw was L−S = 1 at the end of the measuring step.
The amount of heat and kneading applied to the resin material is reduced, and the measured molten resin has non-uniform plasticization.

[0005] It is an object of the present invention to provide a screw-type injection apparatus which eliminates the above-mentioned drawback of the conventional apparatus in that the measured molten resin has non-uniform plasticization.

[0006]

According to the present invention, a nozzle is mounted on one end of a barrel, and a resin material supplied from the other end is melted by a screw mounted on an inner surface of the barrel. In a screw-type injection device that feeds and injects from the nozzle, the nozzle is rotatably mounted while an outer diameter forms a predetermined gap with the inner diameter surface of the barrel, and the nozzle is attached to an axial center that is immovable in the axial direction. A screw provided with a cylindrical portion opened to the side, a plunger slidably fitted in the cylindrical portion of the screw in the axial direction and rotatably with the screw, and provided opposite to the nozzle; While attaching the nozzle, the other end is attached to the barrel tip, one end communicates with the nozzle, and the other end forms an inner diameter surface that forms a gap through which the resin material passes with the screw. A barrel head, which is provided at an inlet portion of the inner surface of the barrel head and which is formed between the barrel head and a screw and allows a resin material to pass therethrough, is closed by a spring force, and resists the spring force during measurement. And a check block which is opened by the pressure of the resin.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a cylindrical portion which is open to the nozzle side at the shaft center of a screw fitted rotatably and immovably in the axial direction while forming a predetermined gap with the inner diameter surface of the barrel. A plunger is slidably inserted in the cylindrical portion in the axial direction and rotatably fitted with the screw, and a plunger is provided to face the nozzle, and the plunger is accumulated from the screw to the front of the plunger in the cylindrical portion during measurement. A screw-type injection device in which the molten resin is injected by the forward movement of the plunger.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described with reference to FIGS. Reference numeral 10 denotes an injection device of the present invention. A nozzle 13 is attached to the tip of a barrel 11 via a barrel head 12, and the other end of the barrel 11 is provided with a resin material in a hopper 14.
A material supply port 15 to be introduced into the inside is provided. Barrel 1
The screw 16 is constrained to move in the axial direction while securing a predetermined gap between the screw 16 and the inner diameter surface, but is freely rotatably fitted. A cylindrical portion 24 is provided at the axis of the screw 16, and the plunger 17 is
Are slidably inserted in a rotational and axial direction by a driving device (not shown).

The plunger 17 has a cylindrical portion 24 at its tip.
And a slidable, but liquid-tight plunger tip 18 is provided, which rotates in synchronism with the screw 16 via a spline 19 provided at the rear end. , And is slidable in the axial direction by a distance S.

One end of the barrel head 12 has the nozzle 1
3 has a funnel-shaped inner surface whose other end is open to the inner surface of the barrel 11, so that a resin passage 20 is formed between the screw 16 and the front surface of the screw 16. As shown in FIG. 4, a check block 21 for opening and closing the resin passage 20 is provided at the entrance of the funnel-shaped inner diameter surface in a circumferential direction.
Normally, the resin passage 20 is closed by the pressing force of the spring 22. However, the screw 16 rotates during the measuring process, and the molten resin material is sent from the screw 16 side. When the pressure exceeds the pressure, it is guided by the guide pin 23 and moves in the axial direction (left direction in the figure), and
Is opened.

The operation is described below. The resin material supplied from the material supply port 15 into the barrel 11 is heated by a heating device provided in the barrel 11 (not shown). While being heated by the device,
The molten resin is melted by shear heat insulation by the screw 16 rotated via the spline 19 of the plunger 17, transferred forward, and pushes the check block 21 closing the resin passage 20 by the pressing force of the spring 22 to open the molten resin. The plunger 17 is accumulated in the cylindrical portion 24 through the resin passage 20 while being retracted.

When a predetermined amount of molten resin is accumulated (hereinafter referred to as a measuring resin) and the plunger 17 is retracted by the stroke S, the rotation of the screw 16 is stopped (completion of the measuring process), and this time, the plunger is injected to inject the measuring resin. 17 moves to the left in the figure, and injects the measurement resin through the nozzle 13 into a mold cavity (not shown).

During this time, the screw 16 rotates but does not move in the axial direction, the plasticization of the metering resin does not become non-uniform, and the resin passage 20 opened during the metering process is moved from the screw 16 side. Since there is no supply of high-pressure resin, it is closed by the pressing force of the spring 22 and there is no backflow from the resin passage 20 side to the screw 16 side.

[0014]

According to the present invention, the metering resin has a uniform plasticization.

[Brief description of the drawings]

FIG. 1 is a view of a screw type injection device showing one embodiment of the present invention at the time of completion of an injection step.

FIG. 2 is a view of a screw type injection device according to an embodiment of the present invention at the time of completion of a measuring step.

FIG. 3 is a view of a screw-type injection device showing one embodiment of the present invention, and is a cross-sectional view taken along line AA of FIG. 1;

FIG. 4 is a view of a screw-type injection device showing one embodiment of the present invention, and is a detailed view of a part 'a' of FIG. 1;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Injection apparatus 11 Barrel 12 Barrel head 13 Nozzle 14 Hopper 15 Material supply port 16 Screw 17 Plunger 18 Plunger tip 19 Spline 20 Resin passage 21 Check block 22 Spring 23 Guide pin 24 Cylindrical part

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[Procedure amendment]

[Submission date] August 27, 1998 (1998.8.2
7)

[Procedure amendment 1]

[Document name to be amended] Statement

[Correction target item name] Fig. 5

[Correction method] Added

[Correction contents]

FIG. 5 is an explanatory view of a conventional screw-type injection device, showing a state in which the screw is advanced (injection completed).

[Procedure amendment 2]

[Document name to be amended] Statement

[Correction target item name] Fig. 6

[Correction method] Added

[Correction contents]

FIG. 6 is an explanatory view of a conventional screw-type injection device, showing a state in which the screw is retracted (metering is completed).

Claims (1)

[Claims] 1. A screw type injection device in which a nozzle is attached to one end of a barrel, and the resin material supplied from the other end is fed to a tip end by a screw mounted on the inner diameter surface of the barrel while being melted, and is injected from the nozzle. A screw provided with a cylindrical portion that opens to the nozzle side at an axis centered on an outer diameter that is rotatably fitted while forming a predetermined gap with the barrel inner diameter surface and that is immovable in the axial direction; A plunger slidably inserted in the axial direction into the cylindrical portion and rotatably with the screw, and a plunger provided opposite to the nozzle, the nozzle is attached to the tip, and the other end is attached to the barrel tip. A barrel head having one end communicating with the nozzle, and the other end having an inner diameter surface that forms a gap through which the resin material passes between the screw and the screw; A check block that is provided at the inlet portion and closes a gap that accumulates in the cylindrical portion through which the resin material formed between the screw and passes by a spring force, and that is opened by a resin pressure against the spring force during weighing. A screw-type injection device comprising: